Our long range goal is to further understand the dynamic interrelationships of the gonads and the anterior pituitary, and how these relationships are conditioned by the hypothalamic-hypophysial-adrenal axis. Studies continue on the effect of increased ACTH and PRL secretion on the post-castration increase of gonadotrophins in both the male and female rat. Further studies on the intervening causative effect of PRL on PB blockade of ovulation are also in progress. We are pursuing the study of the role of FSH during the estrous cycle by using porcine follicular fluid as an agent for selective suppression of FSH. This includes the process of further biochemical and pharmacological identification of the active principle in follicular fluid: "folliculostatin", as well as studies on the mechanism of action of this inhibin-like material.